Date of Award

2007

Degree Type

Thesis

Department

Chemistry

First Advisor

Wei, Robert

Subject Headings

Metallothionein, Common sunflower

Abstract

Metallothioneins (MTs) are ubiquitous low molecular weight, cysteine rich proteins with a pronounced affinity for metal ions with d10 configuration such as Cu, Cd and Zn. These heavy metals form metal-thiolate clusters with cysteine side chains. In contrast to the vertebrate forms, knowledge about the properties of members of the plant metallothionein family is still scarce. We describe here a method of isolation and purification of metallothionein from the plant Helianthus annuus, performed by affinity chromatography using glutathione-agarose column. In this study, alignment of gene sequence of the isolated H. annuus metallothionein cDNA with known MTs showed that it belongs to the type 2 of the plant MTs. The gene sequence encoding MTs was cloned into a suitable vector and the protein was overexpressed in Escherichia coli. The purified metallothionein was evaluated by SDS-PAGE and characterized by UV spectra of the apo-and metal bound protein. Detection of metal bound protein was also carried out by using chemiluminescence assay. The metal binding ability of metallothionein was evaluated by 5, 5 dithio (2-nitrobenzoic acid) (DTNB) analysis. The affinity of metal ions for metallothionein was in the order of Cu>Cd>Zn

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